360 GLOSSARY. 
MoNnoTREMATA (Gr. monos, single; trema, an aperture). The order of 
Mammals, comprising the Duck-mole and the Spiny Ant-eater, in which 
the intestinal canal opens into a ‘‘cloaca” common to the ducts of the 
urinary and generative organs. ' 
MorpHooey (Gr. morphe, form ; logos, discourse). The science of the 
external form and internal structure of the various parts and organs of 
different animals. 
MuLTIVALVE (Lat. multus, many ; valve, folding-doors). Applied to shells 
which are composed of more than two pieces or valves. i 
Myrtapona (Gr. murios, ten thousand ; podes, feet). A class of Articulate 
animals, comprising the Centipedes and their allies, characterised by the 
possession of numerous feet. 
NATATORES (Lat. nare, to swim), The order of the Swimming Birds. 
NatatTory. Adapted for swimming. 
NAUvTILOID. Shaped like the shell of the Nautilus. 
NEOTO-CALYCES (Gr. necho, I swim; kaluz, a cup). The swimming-bells 
of the Oceanic Hydrozoa. 
NEMATODA or NEMATOIDEA (Gr. nema, athread; eidos, form). The divi- 
sion of the Scolecida, comprising the Thread-worms, and Round-worms. 
NERVURES (Lat. nervus, a sinew). ‘The ribs which support the membran- 
ous wings of insects. 
NEURAL (Gr. neuron, a nerve). Connected with the nervous system. 
NEUROPTERA (Gr. newron, a nerve; pteron, a wing). An order of Insects 
in which the wings are membranous and ‘have numerous interlacing 
nervures. 
N ste (Lat. nox, night). Applied to animals which are active at 
night, 
NORMAL (Lat. norma, arule). Conforming to the ordinary standard. 
NorocHorp (Gr. notos, the back ; chordé, a string). A cellular rod which 
is developed in ithe embryo of Vertebrates immediately beneath the 
spina) cord, and which is usually replaced in the adult by the vertebral 
column. : 
Nucieotus. The minute solid particle found in the interior of the 
nucleus of some cells. Also the minute body attached to the exterior 
of the ‘‘nucleus,” of certain of the Infusoria. 
Nuctervus (Lat. akernel), The solid or vesicular body found in the inte- 
rior of many cells ; also the solid rod, or band-shaped body found in the 
interior of many of the Protozoa. 
NUDIBRANCHIATA (Lat. nudus, naked; Gr. bragchia, gills). An order of 
the Gasteropoda in which the gills are naked. 
OcEANIC. Applied to animals which inhabit the open ocean. 
OctopopaA (Gr. octo, eight; podes, feet). The tribe of Cuttle-fishes with 
eight arms round the head. 
ODONTOPHORE (Gr. odous, a tooth; phero, I carry). The so-called 
**tongue ” or masticatory apparatus of the Gasteropoda, Pleropoda, and 
Cephalopoda. 
CisopHAGUS. The gullet, orthe tube by which the food is conveyed from 
the mouth to the stomach. 
OLIGOCHAETA (Gr. oligos, few; chaite, bristles), An order of the Annelida, 
comprising the Karth-worms. 
OmasuM (Lat. bullock’s tripe). The third stomach of Ruminants, com- 
monly called the “‘ psalterium.” 
OmNivornous (Lat. omnia, everything; voro, I devour). Feeding indis- 
criminately upon all kinds of food. 
OPERCULUM (Lat. a lid), The shelly or horny plate by which the shell of 
